Recently, we have shown that hypertensive patients have an impaired vasodilatory response of retinal arterioles to Flickerlight test - which improves after treatment with Angiotensin Receptor Blockers (ARBs) - and have a reduced nitric oxide (NO) activity in the retinal circulation, that is normalized after treatment with ARBs (13; 14). Likewise, in a previous study analyzing the arterial resistance vessels also in the systemic circulation we found that in contrast to diuretics and placebo, valsartan improved endothelial function and vascular properties (estimated by pulse wave anlalysis) (15; 16).